You may have already heard of the tunnels hidden beneath Dupont Circle, the 75,000-square-foot space built in 1949 as an underground streetcar station. It’s been largely uninhabited for decades, but in July, Dupont Underground plans to change that. They’re hoping to transform those dusty passages into a cultural destination, packed with gallery and concert space.

There’s still time to explore the tunnels mostly as they are. On May 30, Atlas Obscura, a travel guide site dedicated to exploring unexpected places, celebrates the world’s weird, hidden wonders with Obscura Day, a worldwide bash involving 150 events in 39 states and 25 countries. For the occasion, Dupont Underground leads three guided walking tours, giving visitors a sense of the space’s history and future.

“The basic core of Atlas Obscura is there’s something incredible to discover where ever you are,” says David Plotz, the former Slate editor who is Atlas Obscura’s CEO. “There’s something that can delight and amaze you, and it’s right around the corner from you.”

Stone rocks from the original US Capitol building were stored in Rock Creek Park during the 1950s. Architecture historian and photographer Bill Lebovich leads a tour through the stones on Saturday. Photo by Bill Lebovich.

Plotz will lead one of the Rock Creek Park tours and take visitors to Fort DeRussy, a defense fort from the Civil War that’s slowly been swallowed by forest. “You’re just walking through the woods and all of a sudden there’s a moat and 12 foot high walls,” he says. “It’s a really strange, magical place right in the middle of the city.”

After his departure from Slate last year, Plotz told theWashington Post about his new gig, saying Atlas Obscura aspires to be the “National Geographic of the 21st century—the digital brand that defines discovery and wonder for our generation.” So how will it achieve that? At a time when every detail about every historical site is available online, Plotz hopes to succeed by introducing people to the surprising things that lurk in plain view. “I really believe the world is more incredible than you think it is,” he says.